Ignore .git folder during test discovery.

On systems with slow hard disks, py.test can seemingly
hang for a noticeable while -- because it's crawling
the .git/ folder; instruct py.test to ignore it.
Change 'ls -l /bin' test to 'uname -m -n ...'

This test intermittently fails on OSX, an example::

    E           -rwxr-xr-x  1 root  wheel   106816 Sep  9 15:49 pax\r
    E         - -rwsr-xr-x  1 root  wheel    46688 Sep  9 15:59 ps\r
    E         + -rwsr-xr-x  1 root  wheel    46688 Sep  9 15:59 ps\r\r
    E         ?                                                     ++
    E           -rwxr-xr-x  1 root  wheel    14208 Sep  9 15:44 pwd\r
Fix test by prevent bash from sourcing profile

Instead, create a temporary file for use with
--rcfile argument with only the contents
``PS1='GO: '``, ensuring that the tests that
expect some form of '[$#]' succeeds even where
a user's default PS1 prompt does not contain it.
write b'bytes' to rcfile, not 'str/unicode'
remove TODO about ls and change to use uname
Make sure when overriding setUp to call super's
Fix 2nd and 3rd expect/response PS1 prompt
Merge pull request #140 from pexpect/occasionally-failing-testcases

Resolve occasionally failing testcases